NAME

       dc - desk calculator

SYNOPSIS

       dc [ file ]

DESCRIPTION

       Dc is an arbitrary precision desk calculator.  Ordinarily it operates on decimal integers,
       but one may specify an input base, output base, and a number of fractional  digits  to  be
       maintained.  The overall structure of dc is a stacking (reverse Polish) calculator.  If an
       argument is given, input is taken from that file until its end,  then  from  the  standard
       input.  The following constructions are recognized:

       number The  value of the number is pushed on the stack.  A number is an unbroken string of
              the digits 0-9A-F or 0-9a-f.  A hexadecimal number  beginning  with  a  lower  case
              letter  must  be  preceded  by a zero to distinguish it from the command associated
              with the letter.  It may be preceded by an underscore _ to input a negative number.
              Numbers may contain decimal points.

       +  - /  *  %  ^
              Add  subtract  multiply  divide remainder or exponentiate the top two values on the
              stack.  The two entries are popped off the stack; the result is pushed on the stack
              in their place.  Any fractional part of an exponent is ignored.

       sx
       Sx     Pop  the  top  of  the  stack and store into a register named x, where x may be any
              character.  Under operation S register x is treated as a stack  and  the  value  is
              pushed on it.

       lx
       Lx     Push  the  value in register x onto the stack.  The register x is not altered.  All
              registers start with zero value.  Under operation L register  x  is  treated  as  a
              stack and its top value is popped onto the main stack.

       d      Duplicate the top value on the stack.

       p      Print  the  top value on the stack.  The top value remains unchanged.  P interprets
              the top of the stack as an text string, removes it, and prints it.

       f      Print the values on the stack.

       q
       Q      Exit the program.  If executing a string, the recursion level  is  popped  by  two.
              Under  operation  Q  the  top value on the stack is popped and the string execution
              level is popped by that value.

       x      Treat the top element of the stack as a character string and execute it as a string
              of dc commands.

       X      Replace the number on the top of the stack with its scale factor.

       [ ... ]
              Put the bracketed text string on the top of the stack.

       <x
       >x
       =x     Pop  and compare the top two elements of the stack.  Register x is executed if they
              obey the stated relation.

       v      Replace the top element on the stack by its square root.  Any  existing  fractional
              part  of  the  argument  is  taken  into account, but otherwise the scale factor is
              ignored.

       !      Interpret the rest of the line as a shell command.

       c      Clear the stack.

       i      The top value on the stack is popped and used as the number base for further input.

       I      Push the input base on the top of the stack.

       o      The top value on the stack is popped and  used  as  the  number  base  for  further
              output.  In bases larger than 10, each `digit' prints as a group of decimal digits.

       O      Push the output base on the top of the stack.

       k      Pop  the  top  of the stack, and use that value as a non-negative scale factor: the
              appropriate  number  of  places  are  printed  on  output,  and  maintained  during
              multiplication,  division,  and  exponentiation.   The interaction of scale factor,
              input base, and output base will be reasonable if all are changed together.

       z      Push the stack level onto the stack.

       Z      Replace the number on the top of the stack with its length.

       ?      A line of input is taken from the input source (usually the terminal) and executed.

       ; :    Used by bc for array operations.

       The scale factor set by k determines how many digits are kept to the right of the  decimal
       point.   If s is the current scale factor, sa is the scale of the first operand, sb is the
       scale of the second, and b is the (integer) second operand, results are truncated  to  the
       following scales.

              +,-  max(sa,sb)
              *    min(sa+sb , max(s,sa,sb))
              /    s
              %    so that dividend = divisor*quotient + remainder; remainder has sign of dividend
              ^    min(sa×|b|, max(s,sa))
              v    max(s,sa)

EXAMPLES

       Print the first ten values of n!

              [la1+dsa*pla10>y]sy
              0sa1
              lyx

SOURCE

       /src/cmd/dc.c

SEE ALSO

       bc(1), hoc(1)

DIAGNOSTICS

       x where x is an octal number: an internal error.
       `Out of headers' for too many numbers being kept around.
       `Nesting depth' for too many levels of nested execution.

BUGS

       When the input base exceeds 16, there is no notation for digits greater than F.

       Past its time.

                                                                                       DC(1plan9)